The study aims to compare the safety and efficacy of LAAM and methadone as maintenance drugs. Sixty-four maintenance clients were randomly assigned to continue on methadone or switch to LAAM for 40 weeks as part of the SAODAP cooperative study, an open trial. Thirty of these subjects are currently participating in the study, and will be asked to continue for an additional 40 weeks of treatment on the drug of their choice, either LAAM or Methadone. Ten women of non-childbearing potential will also be recruited for 40 weeks of LAAM maintenance. For each woman recruited for LAAM treatment a female methadone comparison subject will also be recruited to participate in the same assessment procedures. Comparison women subjects will be matched to the women LAAM subjects on age, duration of addiction, and duration of maintenance treatment. Safety and efficacy will be determined through periodic assessment of symptom complaints and social functioning, urine tests for drugs of abuse, physical examinations, blood and urine analyses, and EKGs.